Dual opposed drive wheels which frictionally engage a ball and propel it through a barrel and towards a batter is disclosed in the prior art ball throwing devices.
One machine discloses a housing enclosing a barrel for the ball, directly opposed drive wheels partially projecting inside the barrel, and drive means for rotating the wheels. Either drive wheel can have a band attached to its circumference. These bands create an uneven surface so that when the wheels grab the ball coming through the barrel, the uneven surface spins the ball about its axis and also imparts a unique trajectory to the ball as it leaves the muzzle end of the barrel. The spin imparted to the ball is important to the batter, because it tends to duplicate the types of balls normally thrown by a pitcher in a baseball game. The pitcher gives "English" to the ball by holding it in a certain way and by tossing it with a particular flick of the wrist, resulting in the commonly designated style pitches such as a curve ball, slider, drop ball, fast ball and the like. Some of these other prior art devices simply lob the ball by pneumatic means without imparting any kind of spin characteristics.
Other prior art devices have directly opposed but separated drive wheels and the ball is fed from a chute into the nip of the wheels. The circumference of the wheels are concave in shape to aid in gripping the ball since there is no barrel to contain the ball. The RPM of either wheel can be adjusted to impart a spin to the axis of the ball. The drive wheels and housing can be tilted to change the trajectory of the ball, or the curve thrown by the ball can be adjusted by radially moving the housing to the left or right in a plane parallel with the ground.
The drawbacks found in these prior art devices is that the device must be realigned each time the batter wishes a different type of pitch be thrown, and the devices must first be adjusted before the device can throw a different type of pitch. Whenever bands are attached to the circumference of the drive wheels, a random but inaccurately thrown pitch results. In order for these devices to be of optimal use in batting practice, the ball must be consistently thrown into the strike zone of the batter. In batting practice, the prior art machines must be reset to place the ball in the strike zone each time the type of pitch is changed. This is time consuming and does not duplicate real playing conditions in a game where the pitcher randomly varies the type of pitch thrown. The time delay for adjustment precludes throwing varying pitches one after the other in quick succession, as in a ball game. It is so time consuming to change pitches that usually no changes are made during a given practice, which may last two hours. One or two changes would be the maximum that would be feasible.
No prior art machine, known to applicant, nas the capacity to tail fast balls in our out, on successive pitches, if at all. This shortcoming is a serious one.